Re: Font, layout units et al.

From: Tomas Frydrych (tomas@frydrych.uklinux.net)
Date: Fri May 24 2002 - 10:41:38 EDT

  • Next message: Martin Sevior: "Re: Font, layout units et al."

    > We then use the same font size at layout resolution when we come to to
    > print. Because we use exactly the same font size for both on-screen
    > and printing we get the same number of lines per page. This actually
    > works.
    >
    > Unfortunately we can't do the same trick to layout text horizontally
    > at layout resolution.
    >
    > The rounding errors associated with scaling the fonts back down to
    > screen resolution make the the widths of the text runs quite different
    > to that at layout resolsution. The text ends up looking really weird
    > on-screen. There are numerous cases of text runs overlapping each
    > other.

    That's because we are not really scaling the fonts. Rather we are
    requesting from the system the font at two different point sizes.
    What we should be doing is to request in both cases the same
    point size, e.g. 12 points, but ask the system to apply a transform
    to the fonts based on the target device resolution, i.e., ~100 dpi for
    the screen and 1440 dpi for the PostScript output. This way the
    fonts would be scaled in a linear fashion and we could just use a
    single system of coordinances. I am pretty sure this can be done
    on Win32 and I would be surprised if it did not work with Xft, or even
    X.

    Tomas



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